void MapSubMatrixIndexedToUnchecked <TU>(DenseColumnMajorMatrixStorage <TU> target, Func <int, int, T, TU> f,
int sourceRowIndex, int targetRowIndex, int rowCount,
int sourceColumnIndex, int targetColumnIndex, int columnCount,
Zeros zeros, ExistingData existingData)
where TU : struct, IEquatable <TU>, IFormattable
{
var processZeros = zeros == Zeros.Include || !Zero.Equals(f(0, 1, Zero));
if (existingData == ExistingData.Clear && !processZeros)
{
target.ClearUnchecked(targetRowIndex, rowCount, targetColumnIndex, columnCount);
}
if (processZeros)
{
CommonParallel.For(0, columnCount, Math.Max(4096 / rowCount, 32), (a, b) =>
{
int sourceColumn = sourceColumnIndex + a;
int targetColumn = targetColumnIndex + a;
for (int j = a; j < b; j++)
{
int targetIndex = targetRowIndex + (j + targetColumnIndex) * target.RowCount;
int sourceRow = sourceRowIndex;
int targetRow = targetRowIndex;
for (int i = 0; i < rowCount; i++)
{
target.Data[targetIndex++] = f(targetRow++, targetColumn, sourceRow++ == sourceColumn ? Data[sourceColumn] : Zero);
}
sourceColumn++;
targetColumn++;
}
});
}
else
{
if (sourceRowIndex > sourceColumnIndex && sourceColumnIndex + columnCount > sourceRowIndex)
{
// column by column, but skip resulting zero columns at the beginning
int columnInit = sourceRowIndex - sourceColumnIndex;
int offset = (columnInit + targetColumnIndex) * target.RowCount + targetRowIndex;
int step = target.RowCount + 1;
int count = Math.Min(columnCount - columnInit, rowCount);
for (int k = 0, j = offset; k < count; j += step, k++)
{
target.Data[j] = f(targetRowIndex + k, targetColumnIndex + columnInit + k, Data[sourceRowIndex + k]);
}
}
else if (sourceRowIndex < sourceColumnIndex && sourceRowIndex + rowCount > sourceColumnIndex)
{
// row by row, but skip resulting zero rows at the beginning
int rowInit = sourceColumnIndex - sourceRowIndex;
int offset = targetColumnIndex * target.RowCount + rowInit + targetRowIndex;
int step = target.RowCount + 1;
int count = Math.Min(columnCount, rowCount - rowInit);
for (int k = 0, j = offset; k < count; j += step, k++)
{
target.Data[j] = f(targetRowIndex + rowInit + k, targetColumnIndex + k, Data[sourceColumnIndex + k]);
}
}
else
{
int offset = targetColumnIndex * target.RowCount + targetRowIndex;
int step = target.RowCount + 1;
var count = Math.Min(columnCount, rowCount);
for (int k = 0, j = offset; k < count; j += step, k++)
{
target.Data[j] = f(targetRowIndex + k, targetColumnIndex + k, Data[sourceRowIndex + k]);
}
}
}
}
